1. Field of the Invention
The present invention relates to a radio frequency power amplifier; in particular, to the radio frequency power amplifier utilizing a three-terminal current source to proceed biasing.
2. Description of Related Art
Handheld devices in a wireless communication, the main direct current (DC) power consumption is from the radio frequency (RF) power amplifier. The RF power amplifier can maintain high linearity without making amplified signal distortion, and simultaneously can present with high efficiency to extend the communication time, so that the RF power amplifier has been a research focus RF power amplifier design. In particular, an orthogonal frequency division multiplexing (OFDM) digital modulation technology widely used in a wireless communication system has obvious characteristics of the time-varying wave packet, its peak value and average power ratio constant (PAPR) is higher than that in conventional wireless communication system. In other words, its wave packet relative to time change is more intense, so the requirements for linearity of the RF power amplifier will be relatively high.
In prior art, the third-generation (3G)/fourth generation (4G) mobile phone system for accuracy of the RF output power has extremely strict requirements. Because voltage value of the phone battery will change significantly, from 3.2 volts to 4.2 volts, therefore the accuracy of the output power for the RF power amplifier will be affected.